Eupsenius, LECONTE

Chandler, Donald S., 2023, The Eupsenius LeConte of North America and the Lesser Antilles with Notes on the Brachyglutini Subtribes Eupseniina Park and Baradina Park (Coleoptera: Staphylinidae: Pselaphinae), The Coleopterists Bulletin 77 (3), pp. 397-412 : 401-402

KEY TO MALES OF THE NORTH AMERICAN SPECIES OF EUPSENIUS LECONTE

Specimen length and geographic location of the collection site are helpful in suggesting species identity, but the ranges and sizes of the species overlap to some degree. The North American species range from 0.9 to 1.5 mm. Females are often slightly larger and more robust than males, but sizes can vary geographically, as well as sexually. There are a few external asexual features that can be sug- gestive for species placement such as size of the vertexal foveae, distinctness of the median indentation of the head base, and distinctness of the pronotal antebasal sulcus and median impression. Form of the male genitalia provides the only reliable confirmation of species identity. Males may be recognized by the presence of a shallow median impression on ventrite 6 (ventrite 6 is the last easily seen ventrite and is longer than the preceding three ventrites) which varies in distinctness within and between species. This impression can be poorly defined for E. dilatatus in particular. Ventrite 6 for females is slightly to distinctly convex and lacks a median impression.

1. Aedeagus in lateral view with basal plate and major portion of shaft nearly parallel, shaft curved 90° from base ( Fig. 4 ); body 0.9–1.0 mm long, body slender when compared with other species; southern Texas ........................ ........ Eupsenius rileyi Chandler , new species

1′. Aedeagus with shaft appearing tubular and evenly curved nearly 180° from base in lateral view ( Figs. 1–3 ); body length 1.1–1.5 mm ..................................................................... 2

2(1). Aedeagus with two lateral recurved spines at apex on morphological left side (right side of illustration), most easily seen in dorsolateral view ( Fig. 2 ); body 1.1–1.2 mm long; North Carolina to Arizona ....................................... ............................. Eupsenius glaber LeConte

2′. Aedeagus with lateral margins straight or slightly curved, lacking lateral spines ( Figs.1, 3 ); body length 1.2–1.5 mm ............................. 3

3(2). Aedeagus in lateral view with two widely separated acute points at apex, dorsal point more prominent than ventral point, points connected by curved to nearly straight margin ( Fig. 1 ); body 1.2–1.5 mm long; northern Ohio to Georgia and east Texas .................................. .................. Eupsenius dilatatus Motschulsky

3′. Aedeagus in lateral view with digitiform tubercle at dorsal apex, apex otherwise truncate ( Fig. 3 ); body 1.2–1.5 mm long; Maine to Florida, one Arizona record ...................... Eupsenius peckorum Chandler , new species

Figures

Figs. 1–5. Eupsenius species, lateral and apicodorsal views of aedeagus. 1) E. dilatatus; 2) E. glaber; 3) E. peckorum, new species; 4) E. rileyi, new species; 5) E. politus.